Field of the Invention
The present invention relates to computing devices and, more particularly, to power sources for personal computers.
Related Art
There is an increasing need for computer systems that are powerful, mobile, and inexpensive. Although mobile computing devices (such as laptop computers and personal digital assistants (PDAs)) and other mobile electronic devices (such as cellular telephones) are typically capable of receiving power either from an electrical outlet or from one or more batteries coupled to and contained within the housing of the device, the advantage of using outlet power is that it provides power for an essentially unlimited period of time. The primary disadvantage of using outlet power is that it ties the computing device to being used within the vicinity of an available outlet and thereby limits the mobility of the device. The advantage of using battery power is that it enables the device to be fully mobile while being used. One disadvantage of using battery power is that an individual battery can only provide power for a limited period of time (such as a few hours). Once a battery runs out of power, the battery must be recharged by connecting the device (or a separate charging station) to an outlet power source, often for several hours, to fully recharge the battery.
One strategy that users often adopt in response to the limited power capabilities of batteries is to travel with several fully-charged batteries, thereby enabling a discharged battery to be immediately replaced with a fully-charged battery without the need to engage in battery charging. Disadvantages of this strategy include the increased cost of additional batteries and the increased burden of traveling with several batteries, thereby effectively decreasing the overall ease of mobility of the mobile computing device.
Larger computing devices, particular those (such as laptop computers) that include power hungry components such as hard disk drives, optical media drives, and color display monitors, typically have significantly higher power requirements than smaller computing devices such as PDAs and tablet computers. Larger computing devices therefore typically require relatively large and heavy batteries, thereby increasing the overall size and weight of the computing device and increasing the burden of traveling with such a device.
Although this problem may be mitigated by decreasing the size of the battery, doing so would result in a battery that discharges more quickly, possibly to an extent that users would find unacceptable. For these and other reasons, the tradeoff between battery size and battery power storage capacity is a persistent feature of mobile computing device design.
What is needed, therefore, are techniques for enabling the implementation of powerful mobile computing devices that are capable of running on battery power for substantial periods of time.